The proposed research is designed to elucidate the molecular nature of the steps in the head assembly of bacteriophage P22 and the regulation of the expression of the genes involved. Emphasis is placed upon understanding the properties and biochemical mechanisms of action of the proteins involved in DNA encapsulation and cutting. Of particular interest is the product of gene 8, which acts catalytically to aid capsid assembly and acts as a type of "molecular scaffold" during assembly, and whose synthesis is apparently negatively autoregulated by some feature of the assembly process. Also under study are the proteins involved in DNA packaging and cutting, gene 2 and 3 proteins. The proteins will be characterized biochemically and functionally by devising in vitro various proteins.